Method, base station and user equipment for radio communication in radio communication system

ABSTRACT

A method, base station, and user equipment (UE) for radio communication in a radio communication system including a base station and a UE, the UE communicating with the base station in carrier aggregation mode over plural component carriers. The method includes: the base station assigns a priority to each component carrier according to at least one of the following rules to enable the UE to select, on overlapped uplink subframes, the component carrier having highest priority for uplink signal transmission, the rules including: desired power loss of uplink signal transmission over the component carrier, burden of uplink signal transmission over the component carrier, number of uplink subframes of the component carrier, and primary/secondary attributes of the component carrier for transmission of a downlink signal corresponding to the uplink signal transmitted over the component carrier. The method, base station, and UE can flexibly adjust the transmission carrier of a PUCCH.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/109,552, filed Jul. 1, 2016, which is based on PCT filingPCT/CN2015/071628, filed Jan. 27, 2015, and claims priority to CN201410042432.9, filed Jan. 28, 2014, the entire contents of each areincorporated herein by reference.

FIELD

The present disclosure relates to the technical field of wirelesscommunication, and in particular to a method, a base station and a UE(User Equipment) for performing wireless communication in a wirelesscommunication system.

BACKGROUND

This section provides background information relating to the presentdisclosure, which is not necessarily prior art.

In traditional intra-base station carrier aggregation, a PUCCH (PhysicalUplink Control Channel) may be transmitted only via an uplink primarycarrier, a PUSCH (physical Uplink Shared Channel) and a SRS (SoundingReference Signal) may be transmitted via a SCC (Secondary ComponentCarrier), and a PRACH (Physical Random Access Channel) may betransmitted only when a terminal is to access a certain carrier.

The following three basic types of carrier aggregation are supported byany version after LTE (Long Term Evolution) Rel-12: 1) the FDD(Frequency Division Duplexing) carrier aggregation, or the TDD (TimeDivision Duplexing) carrier aggregation having the same intra-bandconfiguration; 2) the TDD carrier aggregation having different uplinkand downlink configurations; and 3) the carrier aggregation between FDDand TDD.

In particular, in a case that a larger number of small base stations aredeployed and there exists a direct connection of optical fiber between asmall base station and a macro base station, the traditional methodwhere a PUCCH may be transmitted only via a primary carrier will causesthe following issues for all of the three scenarios above: 1) it cannotshare the burden of PUCCH for a node of a macro base station to releasethe burden of uplink control channel of the macro cell, especially in acase that the uplink time slots of the primary carrier is less and theHARQ (Hybrid Automatic Repeat Request) RTT (Round-Trip Time) of theprimary carrier and a secondary carrier are different (for example, in acase that FDD cooperates with TDD while a TDD carrier serving as aprimary carrier, or in a case of TDD having different configurations; itshould be noted that the number of unlink subframes should be at most60% of the total number of subframes); 2) the power consumption of theuplink transmission is over high when a macro cell carrier servers as aprimary carrier; and 3) in a case that a TDD carrier servers as aprimary carrier and the number of uplink subframes is less, it tends tohave a higher PUCCH feedback time-delay and a higher retransmissiontime-delay of downlink data, effecting the QoS (Quality of Service)feeling of a user.

SUMMARY

This section provides a general summary of the present disclosure, andis not a comprehensive disclosure of its full scope or all of itsfeatures.

The object of the present disclosure is to provide a method, a basestation and a user equipment for performing wireless communication in awireless communication system, which may adjust flexibly a transmissioncarrier for uplink signals, especially for PUCCH, improving thetransmission effectiveness of downlink data while optimizing thetransmission performance of uplink signals.

According to an aspect of the present disclosure, it is provided amethod for performing wireless communication in a wireless communicationsystem, the wireless communication system including a base station and auser equipment, the user equipment communicating with the base stationvia multiple component carriers in a manner of carrier aggregation, themethod including: assigning, by the base station, a priority to eachcomponent carrier such that the user equipment selects a componentcarrier with the highest priority on overlapping uplink subframes totransmit an uplink signal, based on at least one of: an expected powerloss for transmission of the uplink signal on the component carrier; aburden for transmission of the uplink signal on the component carrier;the number of the uplink subframes of the component carrier; andprimary/secondary attribute for a component carrier transmitting adownlink signal corresponding to the uplink signal transmitted on thecomponent carrier.

According to another aspect of the present disclosure, it is provided abase station for performing wireless communication in a wirelesscommunication system, the wireless communication system including thebase station and a user equipment, the user equipment communicating withthe base station via multiple component carriers in a manner of carrieraggregation, the base station including: a priority assigning unit forassigning a priority to each component carrier such that the userequipment selects a component carrier with the highest priority onoverlapping uplink subframes to transmit an uplink signal, based on atleast one of: an expected power loss for transmission of the uplinksignal on the component carrier; a burden for transmission of the uplinksignal on the component carrier; the number of the uplink subframes ofthe component carrier; and primary/secondary attribute for a componentcarrier transmitting a downlink signal corresponding to the uplinksignal transmitted on the component carrier.

According to another aspect of the present disclosure, it is provided auser equipment for performing wireless communication in a wirelesscommunication system, the wireless communication system including a basestation according to the present disclosure and the user equipment, theuser equipment communicating with the base station via multiplecomponent carriers in a manner of carrier aggregation, the userequipment including: a receiving unit for receiving a message on settingand changing of the priority of the component carrier and information ondetermination rule of feedback timing of a PUCCH signal transmitted bythe base station; a selecting unit for selecting a component carrierwith the highest priority among aggregated carriers in which overlappingof uplink subframes occurs, and for selecting scheduling timing of aPUSCH signal and the feedback timing of the PUCCH signal according tothe determination rule of the feedback timing when overlapping ofdownlink subframes occurs in the aggregated carriers; and a transmittingunit for transmitting an uplink signal through the component carrier,the feedback timing of the PUCCH signal, and the scheduling timing ofthe PUSCH signal selected by the selecting unit, or for transmitting anuplink signal according to a component carrier, the feedback timing ofthe PUCCH signal, and the scheduling timing of the PUSCH signaldesignated dynamically by a DCI signaling in the overlapping downlinksubframes.

With the method, the base station and the user equipment for performingwireless communication in a wireless communication system according tothe present disclosure, the user equipment is enabled to, by means ofassigning a priority for each of multiple component carriers, select oneof the multiple component carriers based on the priorities to transmitan uplink signal. Further, feedback timing of overlapping downlinksubframes are determined based on at least one of time-delay requirementof service of the user equipment, energy saving requirement of the userequipment, and implementation complexity. In this way, it is possible toadjust flexibly a transmission carrier for uplink signals, especiallyfor PUCCH, optimizing the transmission performance of uplink signals.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure. In the drawings:

FIG. 1 is a schematic diagram of a scenario of intra-base stationcarrier aggregation;

FIG. 2 is a schematic diagram of a scenario of inter-base stationcarrier aggregation;

FIG. 3 is a schematic diagram of another scenario of inter-base stationcarrier aggregation;

FIG. 4 is a schematic diagram of TDD uplink and downlink configurations;

FIG. 5 is a schematic diagram of downlink HARQ PUCCH feedback timingbased on time-delay;

FIG. 6 is a schematic diagram of downlink HARQ PUCCH feedback timingbased on a criterion of energy saving first;

FIG. 7 is a block diagram of a wireless communication system accordingto an embodiment of the present disclosure; and

FIG. 8 is a block diagram illustrating an exemplary structure of ageneral-purpose personal computer on which the method for performingwireless communication in a wireless communication system according tothe embodiments of the present disclosure can be implemented.

While the present disclosure is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the description herein of specificembodiments is not intended to limit the present disclosure to theparticular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the present disclosure. Note that correspondingreference numerals indicate corresponding parts throughout the severalviews of the drawings.

DETAILED DESCRIPTION OF EMBODIMENTS

Examples of the present disclosure will now be described more fully withreference to the accompanying drawings. The following description ismerely exemplary in nature and is not intended to limit the presentdisclosure, application, or uses.

Example embodiments are provided so that this disclosure will bethorough, and will fully convey the scope to those who are skilled inthe art. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

Below various scenarios to which the technique according to anembodiment of the present disclosure can be applied are described withreference to FIGS. 1 to 3.

FIG. 1 illustrates a scenario of intra-base station carrier aggregation.In the scenario shown in FIG. 1, a UE (User Equipment) 200 communicateswith a macro base station 100 via two component carriers CC1 and CC2 ina manner of carrier aggregation. The coverage area a of the componentcarrier CC1 is larger than the coverage range b of the component carrierCC2, and the frequency bin of the component carrier CC1 is lower thanthat of the component carrier CC2.

FIG. 2 illustrates a scenario of inter-base station carrier aggregation.In the scenario shown in FIG. 2, a UE 200 communicates with a macro basestation 100 via two component carriers CC1 and CC2 in a manner ofcarrier aggregation, and further communicates with a LPN (Low PowerNode) 300 via a component carrier CC3. The coverage area a of thecomponent carrier CC1 is larger than the coverage area b of thecomponent carrier CC2, and the coverage area b of the component carrierCC2 is larger than the coverage area c of the component carrier CC3.Further, the frequency bin of the component carrier CC1 is lower thanthat of the component carrier CC2, and the frequency bin of thecomponent carrier CC2 is lower than that of the component carrier CC3.

FIG. 3 illustrates another scenario of inter-base station carrieraggregation. In the scenario shown in FIG. 3, a UE 200 communicates witha macro base station 100 via a component carrier CC1 in a manner ofcarrier aggregation, and further communicates with a LPN 300 via acomponent carrier CC2 and a component carrier CC3. The coverage area aof the component carrier CC1 is larger than the coverage area b of thecomponent carrier CC2, and the coverage area b of the component carrierCC2 is larger than the coverage area c of the component carrier CC3.Further, the frequency bin of the component carrier CC1 is lower thanthat of the component carrier CC2, and the frequency bin of thecomponent carrier CC2 is lower than that of the component carrier CC3.

FIGS. 1 to 3 only illustrate example scenarios to which the technicalsolution according to an embodiment of the present disclosure can beapplied, and the disclosure is not limited thereto. For example, thenumber of the component carrier for carrier aggregation is not limitedto two or three, and it is possible more than three. In addition, in thescenario shown in FIG. 1, UE 200 communicates with the macro basestation 100 in a manner of carrier aggregation. However, UE 200 may alsocommunicate with LPN 300 in a similar way.

As mentioned in the section of Background, the following three basictypes of carrier aggregation are supported by any version after LTE(Long Term Evolution) Rel-12: 1) the FDD (Frequency Division Duplexing)carrier aggregation, or the TDD (Time Division Duplexing) carrieraggregation having the same intra-band configuration; 2) the TDD carrieraggregation having different uplink and downlink configurations; and 3)the carrier aggregation between FDD and TDD.

In the first type of carrier aggregation, since the HARQ (HybridAutomatic Repeat Request) timing of a primary carrier is the same asthat of a secondary carrier, the original mechanism of performing PUCCH(Physical Uplink Control Channel) feedback based on the primary carrierwill not affect the feedback time-delay and further the QoS (Quality ofService) feeling of a user. Therefore, in a case that the PUCCH capacityof the primary carrier is sufficient (which means all of the downlinkdata transmission can have feedback), a flexible data transmission maybe achieved with all of the downlink resources. In summary, for thefirst type of carrier aggregation, there is no such need to reducefeedback time-delay. It is mainly concerned in the present disclosurehow to share the burden of PUCCH on the primary carrier and how toreduce the power consumption for transmitting an uplink signal by a userequipment.

In the second type of carrier aggregation, if uplink subframes of a TDDprimary carrier is a superset of uplink subframes of a TDD secondarycarrier (that is, downlink subframes of the primary carrier is a subsetof downlink subframes of the secondary carrier), an existing technicalsolution is to follow a downlink HARQ timing of the secondary carrieritself in a case that the secondary carrier performs self-scheduling, orto follow a downlink HARQ timing of the primary scheduling carrier in acase of cross carrier scheduling. Since the uplink subframes of theprimary carrier is a superset of the uplink subframes of other carrier,PUCCH feedback resources can always be obtained from the primary carrierno matter whether the carrier are in individual self-scheduling or incross carrier scheduling, and no matter whether to follows its own PUCCHfeedback timing or follow the PUCCH feedback timing of the primaryscheduling carrier. Therefore, the downlink resources of the secondarycarrier will not be wasted as long as the self-scheduling is adopted fornon-overlapping subframes and the cross carrier scheduling or theself-scheduling is adopted for overlapping subframes.

Further, if uplink subframes of a TDD primary carrier is a subset ofuplink subframes of a TDD secondary carrier (that is, downlink subframesof the primary carrier is a superset of downlink subframes of thesecondary carrier), the existing technical solution is to follow thedownlink HARQ timing of the primary carrier no matter whether thesecondary carrier is in the cross carrier scheduling or in theself-scheduling. Although the downlink resources of the secondarycarrier will not be wasted in this way, the overall feedback time-delayincreases because of the less uplink time slots of the primary carrier,especially for some downlink subframes in configurations 2-5.

FIG. 4 illustrates seven different configurations for TDD uplink anddownlink, in which a shaded grid represents a downlink subframe, and anon-shaded grid represents an uplink subframe. A number n in anon-shaded grid indicates that A/N information of the present uplinksubframe is obtained based on the downlink data feedback of previous nsubframes. Among the seven configurations, the combinations ofconfigurations {1, 3}, {2, 3} and {2, 4} are neither in a supersetrelation nor in a subset relation between uplink and downlink subframes.The combination of configuration {1, 3} follows the downlink HARQ timingof configure 4, and the other two combinations follow the downlink HARQtiming of configure 5. Such adjustment of timing enables all of theaggregated downlink resources to be scheduled, but also results insharply rising uplink feedback burden of uplink subframe 2 and/or uplinksubframe 3. Especially in the case of configuration 5 where only 1uplink feedback subframe exists, the feedback may be performed only byA/N Bundling (i.e., A is fed-back only if all of downlink subframes arereceived correctly, otherwise N is fed-back). This may result inunnecessary downlink retransmission, and also a jam of uplink feedbackresources of a feedback carrier because the burden of PUCCH feedbackcannot be shared to other time slots.

Particularly, in a case of the third type, i.e., the FDD-TDD carrieraggregation, if a TDD carrier serves as a primary carrier, it ispossible that corresponding uplink transmission resources cannot beobtained when following downlink HARQ transmission timing of FDD,because less carrier resources are configured for the TDD carrier. Inthis case, in addition to adding the uplink feedback burden of the TDDprimary carrier, it may cause a waste of some of the FDD downlinkresources (because of discarding of downlink transmission due to lack ofcorresponding uplink resources for feedback), or failing to retransmiteffectively following the FDD downlink HARQ timing (because feedbackcannot be obtained even when downlink transmission is performed and thusit is impossible to retransmit).

Therefore, it is desired to provide a technical solution to performwireless communication in a wireless communication system, by which atransmission carrier for uplink signals, especially for PUCCH, may beselected dynamically in order to ensure the transmission effectivenessof the network with limited PUCCH capacity, and which may also beadjusted dynamically based on at least one of load condition of PUCCH ofa cell and the power consumption of PUCCH transmission of a terminal.Further, the dynamic adjustment for the PUCCH transmission will resultin changes about feedback time slot of downlink HARQ in the above secondand third types of carrier aggregation. Thus, such issue is alsoconsidered in the present disclosure to optimize a design fortransmission via air interface.

According to an embodiment of the present disclosure, there is provideda method for performing wireless communication in a wirelesscommunication system. As shown in FIGS. 1 to 3, the wirelesscommunication system includes a base station, such as a macro basestation 100 and/or a LPN 300, and user equipment, such as UE 200. Theuser equipment communicates with the base station via multiple componentcarriers, such as CC1, CC2 or CC3, in a manner of carrier aggregation.The method includes assigning by the base station a priority to eachcomponent carrier based on at least one of an expected power loss fortransmission of the uplink signal on the component carrier, a burden fortransmission of the uplink signal on the component carrier, the numberof the uplink subframes of the component carrier, and primary/secondaryattribute for a component carrier transmitting a downlink signalcorresponding to the uplink signal transmitted on the component carrier.The user equipment is enabled to select a component carrier with thehighest priority on overlapping uplink subframes to transmit an uplinksignal.

In the method according to the embodiment of the present disclosure, thePUCCH is not limited to transmit via only a uplink primary carrier, butmay transmit via one of multiple carriers selected based on thepriorities. In this way, the transmission carrier of the PUCCH may beadjusted flexibly, optimizing the transmission performance of thedownlink data and PUCCH.

According to an embodiment of the present disclosure, the uplink signalmay include at least one of a PUCCH signal and a PUSCH (Physical UplinkShared Channel) signal. Further, the base station may include at leastone of a macro base station and a low power node.

In the method according to an embodiment of the present disclosure, whenthe priority is assigned based on the number of the uplink subframes ofthe component carrier, a higher priority may be assigned to a componentcarrier with more uplink subframes. Specifically, the priority of a FDDcarrier may be higher than that of a TDD carrier. In addition, TDDcomponent carriers in the following configurations may have lowerpriorities in an order: configuration 0, configuration 6, configuration1, configuration 3, configuration 4 and configuration 5. A TDD componentcarrier in configuration 2 may have the same priority as a TDD componentcarrier in configuration 4.

In the method according to an embodiment of the present disclosure, whenthe priority is assigned based on the primary/secondary attribute forthe component carrier transmitting the downlink signal, if the componentcarrier transmitting the downlink signal is a primary component carrier,then a higher priority may be assigned to the corresponding componentcarrier transmitting the uplink signal. Correspondingly, if thecomponent carrier transmitting the downlink signal is a secondarycomponent carrier, then a lower priority may be assigned to thecorresponding component carrier transmitting the uplink signal.

In the method according to an embodiment of the present disclosure, whenthe priority is assigned based on the burden for transmission of theuplink signal on the component carrier, a lower priority may be assignedto a component carrier providing a larger coverage area and/or providingservice for more user equipments. Correspondingly, a higher priority maybe assigned to a component carrier providing a smaller coverage areaand/or providing service for less user equipments. The base station maydetermine the coverage area of a carrier based on the magnitude of theband of the carrier and a factor such as whether a relay amplifier isconfigured. Generally, a carrier in a lower band has a larger coveragearea, and a carrier which is in the same band as other carriers and isconfigured with a relay amplifier has a larger coverage area.

In the method according to an embodiment of the present disclosure, whenthe priority is assigned based on the expected power loss fortransmission of the uplink signal on the component carrier, a higherpriority may be assigned to a component carrier with a lower expectedpower loss. Further, the expected power loss is determined based on thecoverage area of the carrier and/or downlink path loss. For example, ina case that the base station includes only one of a macro base stationand a LPN, a higher priority may be assigned to a component carrier witha lower frequency bin. In a case that the base station includes both themacro base station and the LPN, a higher priority may be assigned to acomponent carrier belonging to the LNP.

According to an embodiment of the present disclosure, in a case that theuplink signal is a PUCCH signal and the PUCCH signal contains feedbackinformation, the base station may further assign the priority based onfeedback time-delay of the PUCCH signal of the component carrier.

In the method according to an embodiment of the present disclosure, whenthe priority is assigned based on the feedback time-delay of the PUCCHsignal of the component carrier, a FDD component carrier may have ahigher priority than a TDD component carrier.

In addition, TDD component carriers in the following configurations mayhave lower priorities in an order: configuration 0, configuration 1,configuration 6, configuration 3, configuration 4 and configuration 5. ATDD component carrier in configuration 2 may have the same priority as aTDD component carrier in configuration 3.

For example, when a PUCCH resource is transmitted via overlapping uplinksubframes on an intra-base station aggregated carrier, in the casesshown in FIGS. 1 and 2, the overall power consumption for PUCCH feedbackof the component carrier CC1 should be lower than that of componentcarrier CC2. However, the PUCCH feedback burden of component carrier CC1is higher than that of component carrier CC2 because the coverage areaof component CC1 is larger. Thus, a priority for PUCCH feedback ofcomponent carrier CC2 may be assigned higher than that of componentcarrier CC1 for some carrier aggregation terminals. When UE 200 in FIG.2 is in inter-base station carrier aggregation, both the PUCCH burdenand feedback consumption of component carrier CC3 are the least due tothe distance from UE 200 and its coverage area. Therefore, the feedbackpriorities in FIG. 2 may be assigned as: CC3>CC2>CC1.

Similarly, when a PUCCH resource is transmitted via overlapping uplinksubframes on an intra-base station aggregated carrier, in the case shownin FIG. 3, the power consumption for PUCCH feedback of the componentcarrier CC2 should be lower than that of component carrier CC3 ingeneral. Meanwhile, the overall PUCCCH feedback burden is not high dueto the less number of users of LPN 300. Thus, a priority for PUCCHfeedback of component carrier CC2 may be assigned higher than that ofcomponent carrier CC3. When UE 200 in FIG. 3 is in inter-base stationcarrier aggregation, both the PUCCH burden and feedback consumption ofcomponent carrier CC1 are the most due to the distance from UE 200 andits coverage area. Therefore, the feedback priorities in FIG. 3 may beassigned as: CC2>CC3>CC1.

According to an embodiment of the present disclosure, the base stationmay notify the user equipment of a message on setting and changing ofthe priority of the component carrier via a RRC (Radio Resource Control)signaling or a MAC (Media Access Control) signaling.

That is, when the priority is changed, the base station may notify theuser equipment of the change in priority via a RRC signaling or a MACsignaling.

Thereby, the user equipment is enabled to select a component carrierwith the highest priority to transmit an uplink signal.

It should be noted that the base station in the present disclosure mayevaluate the priority of a component carrier based on multiple rules.Specifically, for example, it is possible to evaluate prioritiesrespectively based on multiple rules and then determine comprehensivelya finial priority based on the multiple evaluated results, or it ispossible to select a rule among the multiple rules dynamically accordingto specific conditions and evaluate a priority based on the selectedrule. Furthermore, the rule for evaluating a priority by the basestation in the present disclosure may be static. For example, the basestation may evaluate a priority fixedly based on at least one rule amongothers. The above cases will not be described in detail.

It is described above the dynamic adjustment among multiple componentcarriers for transmitting uplink signals. As mentioned above, thedynamic adjustment for uplink signals such as PUCCH will result inchanges in feedback time slot of downlink HARQ in the above second andthird types of carrier aggregation. It will be described below how todeal with such issue to optimize a design for transmission via airinterface. It should be noted that the following technical solution doesnot necessarily rely on the above uplink dynamic adjustment solution,and may be implemented separately to solve a corresponding technicalproblem.

The uplink transmission resources that may be obtained in time domain byan aggregated carrier are a union of that of all the aggregatedcarriers. Thus, in a case of supporting dynamic PUCCH feedbackadjustment, each TDD carrier may determine its PUCCH feedback time slotbased on the transmission timing of its downlink PDSCH (PhysicalDownlink Shared Channel), and may follow its PUCCH feedback timing for anon-overlapping downlink subframe. Among the aggregated carriers, all ofFDD carriers follow the same timing, and all of TDD carriers with thesame uplink and downlink configuration follow the same timing.Meanwhile, when the PUCCH feedback timing is determined, the PUSCHscheduling timing of individual carrier may be remaining the same as thePUCCH feedback timing or following the original PUSCH scheduling timing.

According to an embodiment of the present disclosure, when there areoverlapping downlink subframes among the multiple component carriers andthere is transmission of PDSCH on the overlapping downlink subframes,the base station and/or the user equipment may determine feedback timingof a PUCCH signal corresponding to the component carrier for which thereis the transmission of PDSCH on the overlapping downlink subframes,based on at least one of: feedback timing of a component carrier withthe highest priority among uplink component carriers corresponding tothe component carrier for which there is the transmission of PDSCH onthe overlapping downlink subframes; feedback timing of a componentcarrier with the lowest feedback time-delay among uplink componentcarriers corresponding to the component carrier for which there is thetransmission of PDSCH on the overlapping downlink subframes; feedbacktiming of a primary scheduling component carrier in a process of crosscarrier scheduling; and feedback timing of the component carrier per sefor which there is the transmission of PDSCH on the overlapping downlinksubframes.

Preferably, in a case that the feedback timing of the PUCCH signal isdetermined based on the feedback timing of the component carrier withthe highest priority or the feedback timing of the component carrierwith the lowest feedback time-delay, if obtained time-delay gain oruplink transmission power gain is lower than a predetermined thresholdand the number of downlink subframes associated with uplink subframesfor transmitting the PUCCH signal of the component carrier is caused tobe increased and exceed two, the feedback timing of the componentcarrier per se for which there is the transmission of PDSCH on theoverlapping downlink subframes may be selected as the feedback timing ofthe PUCCH signal.

Furthermore, the base station may select, as scheduling timing of aPUSCH signal of the component carrier on the overlapping downlinksubframes corresponding to the overlapping downlink subframes, one of:feedback timing of the PUCCH signal of the component carrier; andscheduling timing of the PUSCH signal of the current component carrier.

According to an embodiment of the present disclosure, the base stationmay determine the rule of the feedback timing of the PUCCH signal basedon at least one of time-delay requirement of the downlink signal, energysaving requirement of the user equipment, and implementation complexity.

Further, the base station may notify the user equipment of thedetermination rule of the feedback timing of the PUCCH signal with whichthe component carrier is to comply via a RRC signaling or a MACsignaling.

Furthermore, when it is required to adjust dynamically the PUCCHfeedback carrier and/or the PUCCH feedback timing of the componentcarrier performing PDSCH transmission on the overlapping downlinksubframes, the PUCCH feedback carrier on the overlapping downlinksubframes and/or the feedback timing of the PUCCH signal correspondingto the PDSCH transmission of the component carrier may be designateddynamically by utilizing newly added bit information or redundancy forDCI (Downlink Control Information) of PDSCH scheduling.

For example, the PUCCH feedback carrier on the overlapping downlinksubframes and/or the feedback timing of the PUCCH signal correspondingto the PDSCH transmission of the component carrier may be designated byadding a bit to the DCI.

Below, the case of carrier aggregation between FDD and TDD, i.e., thethird type of carrier aggregation will be described first in detail.

The PUCCH feedback of a TDD aggregated carrier may be performedfollowing the original timing or the FDD timing. For example, in a casethat a TDD carrier is in configuration 5, if the PUCCH feedback isperformed following the original timing, the downlink transmissiontime-delay is much longer than following the FDD timing, and there is aneed using A/N Bundling, so as to decrease the accuracy of feedback.However, in a case that a TDD carrier is in configuration 0, performingthe feedback following the original timing is not so different fromperforming the feedback following the FDD timing. Therefore, in the caseof carrier aggregation between FDD and TDD, the configurations where thenumber of the association between uplink subframe and downlink subframesis more than 2, are configurations 2, 3, 4 and 5 in FIG. 4, the carrierswith these configurations preferably follows the FDD timing in order toavoid A/N Bundling and a long time-delay. The configurations other thanconfiguration 0 each has a RTT (Round-Trip Time) of downlink HARQ timingmore than 10 ms, for which it is advantageous for reducing thetime-delay of retransmission of data and improving the Qos feeling forreal-time services if performing the feedback by following the FDDtiming. A FDD carrier only follows its own downlink HARQ feedbacktiming.

However, in a case of inter-base station carrier aggregation, assuming aFDD carrier servers as a macro carrier and a TDD carrier servers as aserving carrier of LPN, if following the timing of the FDD carrier, thefeedback is performed via the TDD carrier for overlapping uplinksubframes and via the FDD carrier for a non-overlapping uplink subframe,which case has more power consumption than the case that UE performsPUCCH feedback on the TDD carrier following the TDD timing for anoverlapping downlink subframe. For example, in the case that a FDDcarrier serves as a macro base station carrier and a TDD carrier in theuplink and downlink configuration 5 servers as a low power node carrier,if the TDD carrier performs the HARQ feedback following the FDD timing,only subframe 2 can perform PUCCH feedback, apparently increasinggreatly the power consumption of the UE. Therefore, in this case, fortransmission of downlink non real-time service, it is more advantageousfor saving the PUCCH transmission power of the UE if the TDD carrierfollows its own PUCCH feedback timing or the PUCCH feedback timing ofanother TDD carrier of the same node. The FDD macro carrier is moresuitable for transmitting real-time services because of the ability ofensuring a lower PUCCH feedback time-delay. Especially, when the UE mayuse multiple aggregated TDD carriers of the LPN, it is possible toselect the PUCCH feedback timing of a carrier with a lower frequency binamong the TDD carriers of the LPN for overlapping downlink subframes inorder to reduce the power consumption of the UE for feedback, or selectthe PUCCH feedback timing with lower time-delay in the LPN, or followthe PUCCH feedback timing of a primary scheduling carrier in a case thatthe cross carrier scheduling is adopted within the LPN.

In the above cases, a static feedback timing of a TDD carrier isdetermined based on criterions of time-delay requirement of a service,energy saving requirement of a terminal, and implementation complexity.The base station may notify the UE of a static timing that should befollowed by individual aggregated carriers or all of aggregated carriersvia RRC/MAC signaling. Under the requirements of energy saving,time-delay and load sharing of PUCCH, the PUCCH feedback timing ofoverlapping downlink subframes may be adjusted dynamically. That is, theDCI of PDSCH scheduling followed by the subframe may designatedynamically the downlink subframe should follow the PUCCH feedbacktiming of which TDD configuration/aggregated carrier.

Next, the case of the TDD carrier aggregation having different unlinkand downlink configurations, i.e., the second type of carrieraggregation will be described in detail.

Mostly different from a FDD carrier in the carrier aggregation betweenFDD and TDD, a TDD carrier which has a position of superset for unlinksubframes has a position of subset for the downlink subframes, while theFDD carrier has a position of superset for both uplink subframes anddownlink subframes with respect to a TDD carrier; and a TDD uplinkcarrier in a superset does not necessarily just follow its own PUCCHfeedback timing. In the case of TDD carrier aggregation having differentunlink and downlink configurations, in addition to following its ownfeedback timing, a TDD carrier may, for example, select an uplink timeslot with a short feedback time to transmit PUCCH if an overlappingdownlink subframe has multiple time points for feedback, or follow thetiming of a primary scheduling carrier in a case of cross carrierscheduling, or follow the timing of a carrier of a node with lower powerconsumption, or the uplink feedback timing may follow a PUCCH feedbacktiming of a uplink and downlink configuration where the number andpositions of subframes in the intersection set of uplink subframes arethe same in a case that the uplink and downlink subframes of anaggregated carrier are not in a superset or subset relation.

FIG. 5 shows an exemplary determined PUCCH feedback timing for aspecific set of carrier aggregation configurations complying with acriterion of least feedback time which is suitable for a real-timeservice and a further optimized technical solution. In FIG. 5, a shadedgrid represents a downlink subframe, and a non-shaded grid represents anuplink subframe. A number n in a non-shaded grid indicates that A/Ninformation of the present uplink subframe is obtained based on thedownlink data feedback of previous n subframes. Further, in FIG. 5, in agrid without a blanket, a numerical value indicates a numerical value ofthe original timing, and in a grid with a blanket, a numerical valueinside the blanket indicates a numerical value of the original timing,and a numeric value outside the blanket indicates a numerical value ofadjusted timing. Here, the basic principle for adjusting a numericalvalue of a downlink subframe is to take a smaller numerical value whencomparing among different configurations.

Referring to Table 1 in FIG. 5, in a case that aggregated carriers arein an uplink superset or subset relation, it can be seen that inconfiguration 6_A, the saved time-delay of the downlink subframes forwhich timing is changed are all greater than or equal to 3 ms, exceptsubframe 6. Subframe 6 in configuration 6, which follows the timing ofconfiguration 3 after adjusted, saves 1 ms, having limited effect on theQoS of real-time data transmission. Thus, subframe 6 may remain thefeedback timing unchanged, i.e., follow the feedback timing inconfiguration 6_B.

Referring to Table 2 in FIG. 5, in a case that an aggregated carriersare not in an uplink superset or subset relation (i.e., a combination ofonly configurations 1 and 3), if complying with the criterion ofoptimizing the feedback time-delay, subframe 9 may only save atime-delay of 1 ms (as configuration 3_B). However, the number offeedback time slots of subframe 3 in configuration 3_B is increased.Furthermore, in a case that an uplink subframe supports the doublecodeword feedback without performing A/N Bundling, an uplink subframemay be associated with at most two downlink subframes at once. Subframe3 in configuration 3 B is changed to be associated with three subframesrather than the original two subframes, thereby having to performing A/NBundling to support the most numbers of feedback subframes andcodewords. In this case, if subframe 9 remains the original schedulingas configuration 3, it can be ensured that no A/N Bundling needs to beperformed for any PUCCH feedback in the combination. Therefore,configuration 3_A in Table 2 is a better resultant timing adjustment.

Further, assuming adding an aggregated carrier in configuration 4, thetiming of configuration 1 or 3 does no change while the time-delay ofsubframe 6 and subframe 8 in configuration 4 can be optimized by 1 ms.It can be seen from the four configuration options, performingtime-delay optimization on at least one subframe is better thanremaining original PUCCH feedback timing for all of subframes. Thereason is, among subframe 2 and subframe 3, a subframe that is possibleto perform A/N Bundling has only 3 associated downlink carriers, whilesubframe 3 in configuration 4_B in Table 2 has 4 associated downlinkcarriers, increasing greatly the possibility of A/N Bundling.

Referring to Table 3 in FIG. 5, in a case of configuring the carrieraggregation of configurations 2, 3 and 4, the time-delay of subframe 6and subframe 8 in configuration 4 can still be optimized by 1 ms. In acase of remaining unchanged or optimizing for all of subframes, only oneuplink subframe may possibly need to perform A/N Bundling, but thisuplink subframe needs to be associated with 4 downlink subframes, havinga higher possibility of A/N Bundling. However, if performing the PUCCHfeedback time-delay optimization for only subframe 6 or subframe 8, thensubframe 2 and subframe 3 each have the possibility of A/N Bundlingbecause each of them is associated with 3 downlink subframes.

In a case of transmission of non real-time service, the PUCCH feedbacktiming of a carrier with the least power consumption may be followed foroverlapping downlink subframes. Alternatively, the multiple optionalPUCCH feedback timing of overlapping downlink subframes may be ranked inthe ascending order according to their time-delay, and the feedbacktiming with the lowest time-delay may be selected to be followed ifcorresponding uplink resources can be obtained on a carrier or a carriercluster when following the feedback timing with the lowest time-delay.In this way, the timing adjustment as shown in Table 6 of FIG. 6 may beobtained.

FIG. 6 illustrates downlink HARQ PUCCH feedback timing based on thecriterion of energy saving first. Similarly, in FIG. 6, a shaded gridrepresents a downlink subframe, and a non-shaded grid represents anuplink subframe. A number n in a non-shaded grid indicates that A/Ninformation of the present uplink subframe is obtained based on thedownlink data feedback of previous n subframes. Further, in FIG. 6, in agrid without a blanket, a numerical value indicates a numerical value ofthe original timing, and in a grid with a blanket, a numerical valueinside the blanket indicates a numerical value of the original timing,and a numeric value outside the blanket indicates a numerical value ofadjusted timing.

The following is described with an example of two aggregated carriers inconfiguration {3,6} (the embodiment may be applicable to any cases ofcarrier aggregation having a configuration in uplink superset or subsetrelation). If the carrier in configuration 6 serves as an uplink carrierwith lower power consumption, the simplest adjustment is that thecarrier in configuration 3 completely follows the PUCCH feedback timingof the carrier in configuration 6 for any overlapping downlinksubframes, as shown in Table 1 of FIG. 6. However, time-delay is addedunnecessarily for time slot 0 because, when following the timing of thecarrier in configuration 3, subframe 4 of the carrier in configuration 6may be also used for PUCCH feedback of subframe 0. Further, theadjustment to the timing of subframe 6 results in added time-delay of 1ms. Among multiple optional PUCCH feedback timing for overlappingdownlink subframes, the downlink subframes 0, 1, and 6 have differentPUCCH feedback time slot, but all have corresponding uplink resources onthe low power consumption carrier in configuration 6 which is configuredbased on the criterion of least time-delay. Therefore, the timing may beadjusted as Table 2 of FIG. 6. Certainly, it may remain following theoriginal feedback timing since only 1 ms is saved for the time-delay ofsubframe 6 of the carrier in configuration 6.

In the scenario of inter-base station carrier aggregation, if anaggregated carrier of a macro base station is in configuration 1, andtwo aggregated carriers of a LPN are in configurations 2 and 3respectively in which the carrier in configuration 2 has a lowerfrequency bin than the carrier in configuration 3, then their powerconsumption is in an order as configuration 2, configuration 3 andconfiguration 1. Since the carriers in configurations 2 and 3 belong tothe LPN, the difference between their PUCCH transmission power should bebelow a certain threshold, and thus the carriers in configurations 2 and3 may be considered as a carrier cluster with low power consumption.

Referring to Table 3 of FIG. 6, if all of overlapping downlink carriersfollows the PUCCH feedback timing of a carrier with the lowest powerconsumption, the time-delay of subframes 0 and 9 can be optimized by acertain extent, and the feedback capacity of subframe 2, 3 and 4 can beoptimized by a certain extent (i.e., subframe 2 in configuration 3 has 3associated downlink subframes, having a possibility of A/N Bundling,while the other two uplink subframes in configuration 3 each havesufficient feedback capacities for not performing A/N Bundling).

Further, if the criterion is changed to be that, among multiple optionalPUCCH feedback timing for overlapping downlink subframes, an inter-basestation overlapping downlink carrier, when appearing, follows thefeedback timing of a carrier of the carrier cluster with the lowestpower consumption which has the lowest feedback time-delay. In thiscase, if only an intra-base station overlapping downlink carrierappears, it follows the feedback timing with the lowest time-delay,thereby obtaining the timing adjustment as shown in Table 4 of FIG. 6.

However, the feedback capacity of subframes 2 and 4 in configuration 3can be still optimized by a certain extent (i.e., subframe 2 inconfiguration 3 has 3 associated downlink subframes, having apossibility of A/N Bundling, while subframes 4 has sufficient feedbackcapacities for not performing A/N Bundling). Therefore, for downlinksubframe 8 in configuration 3 of Table 4, corresponding uplink resourcesmay be obtained on the carrier cluster with low power consumption iffollowing the original PUCCH feedback timing, with only 1 ms of extratime-delay compared with the optimal time-delay, which will not resultin an obvious effect on the service transmission. Table 5 of FIG. 6shows the adjustment result.

Alternatively, the multiple optional PUCCH feedback timing ofoverlapping downlink subframes may be ranked in the ascending orderaccording to their time-delay, and the feedback timing with the lowesttime-delay may be selected to be followed if corresponding uplinkresources can be obtained on a carrier or a carrier cluster whenfollowing the feedback timing with the lowest time-delay. In this way,the timing adjustment as shown in Table 6 of FIG. 6 may be obtained.

However, the feedback capacity of subframes 2 and 4 in configuration 3can be still optimized by a certain extent (i.e., subframe 2 inconfiguration 3 has 3 associated downlink subframes, having apossibility of A/N Bundling, while subframes 4 has sufficient feedbackcapacities for not performing A/N Bundling). Therefore, for downlinksubframes 8 and 9 in configuration 3 of Table 6, corresponding uplinkresources may be obtained on the carrier cluster with low powerconsumption if following the original PUCCH feedback timing, with only 1ms of extra time-delay compared to the optimal time-delay, which willnot result in an obvious effect on the service transmission. Table 7 ofFIG. 6 shows the adjustment result.

In the above cases, a static feedback timing of a TDD carrier isdetermined based on criterions of time-delay requirement of a service,energy saving requirement of a terminal, and implementation complexity.The base station may notify the UE of a static timing that should befollowed by individual aggregated carriers or all of aggregatedcarriers. Under the requirements of energy saving, time-delay and loadsharing of PUCCH, the PUCCH feedback timing of an overlapping downlinksubframe may be adjusted dynamically. That is, the DCI of PDSCHscheduling of the subframe may design dynamically the downlink subframeshould follow the PUCCH feedback timing of which TDDconfiguration/aggregated carrier.

If it is required to achieve dynamic timing adjustment and send asignaling for selected feedback carrier together with downlink data, itis possible to add 5 bits to DCI to notify of which carrier is selectedfor feedback in a manner of bitmap (for example, the carriers arenumbered in a descending or ascending order according to their frequencybins, and the value 0 or 1 of a bit indicates that the carrier having anumber corresponding to the bit does not perform PUCCH feedback, and thevalue 1 or 0 of a bit indicates that the carrier having a numbercorresponding to the bit performs PUCCH feedback) since a terminalcurrently supports at most 5 aggregated carriers. If further definingthat the PUCCH feedback timing follows the timing of feedback carrier, 5bits is sufficient to achieve the dynamic timing adjustment and feedbackcarrier adjustment. Otherwise, if it is required to adjust the defaultfeedback timing, 5 extra bits are needed to specify the feedback timingof which carrier is to be followed.

Further, since the default feedback carrier and the carrier whose timingis followed by the default feedback carrier are known, the bitmap of 5bits in the above example can be reduced to a bitmap of 4 bits todistinguish the other aggregated carriers. Alternatively, 2 bits may befurther used to identify the carrier that performs PUCCH feedback or thecarrier whose PUCCH feedback timing is to be followed.

According to an embodiment of the present disclosure, in a case ofcarrier aggregation in a wireless communication system, the downlinkHARQ A/N feedback timing is adjusted based on multiple PUCCH feedbacktime points of overlapping downlink subframes of aggregation carriers,and the transmission carrier of PUCCH is adjusted flexibly based onoverlapping uplink subframes, thereby optimizing the transmissionperformance of downlink data and PUCCH.

Below a wireless communication system according to an embodiment of thepresent disclosure is described with reference to FIG. 7. Referring toFIG. 7, the wireless communication system according to an embodiment ofthe present disclosure includes a base station 100 and user equipment200, the user equipment 200 communicating with the base station 100 viamultiple component carriers in a manner of carrier aggregation. The basestation 100 may include but not be limited to a priority assigning unit110, a transmitting unit 120, a determining unit 130, a notifying unit140, a designating unit 150 and a receiving unit 160, and the like. Theuser equipment 200 may include but not be limited to a receiving unit210, a selecting unit 220 and a transmitting unit 230, and the like.

The priority assigning unit 110 may assign a priority to each componentcarrier such that the user equipment 200 selects a component carrierwith the highest priority on overlapping uplink subframes to transmit anuplink signal, based on at least one of: an expected power loss fortransmission of the uplink signal on the component carrier; a burden fortransmission of the uplink signal on the component carrier; the numberof the uplink subframes of the component carrier; and primary/secondaryattribute for a component carrier transmitting a downlink signalcorresponding to the uplink signal transmitted on the component carrier.

Preferably, the uplink signal may include at least one of a PUCCH signaland a PUSCH signal, and/or the base station 100 may include at least oneof a macro base station and a low power node.

Preferably, when the priority is assigned by the priority assigning unit110 based on the number of the uplink subframes of the componentcarrier, a higher priority may be assigned to a component carrier withmore uplink subframes.

Preferably, when the priority is assigned by the priority assigning unit110 based on the primary/secondary attribute for the component carriertransmitting the downlink signal, if the component carrier transmittingthe downlink signal is a primary component carrier, then a higherpriority may be assigned to the corresponding component carriertransmitting the uplink signal.

Preferably, when the priority is assigned by the priority assigning unit110 based on the burden for transmission of the uplink signal on thecomponent carrier, a lower priority may be assigned to a componentcarrier providing a larger coverage area and/or providing service formore user equipments.

Preferably, when the priority is assigned by the priority assigning unit110 based on the expected power loss for transmission of the uplinksignal on the component carrier, a higher priority may be assigned to acomponent carrier with a lower expected power loss.

Preferably, when the priority is assigned by the priority assigning unit110 based on the expected power loss for transmission of the uplinksignal on the component carrier, if the base station 100 only includesonly one of a macro base station and a low power node, a higher prioritymay be assigned to a component carrier with a lower frequency bin, andif the base station 100 includes both of a macro base station and a lowpower node, a higher priority may be assigned to a component carrierbelonging to the low power node.

Preferably, the uplink signal may be the PUCCH signal and the PUCCHsignal may contain feedback information, and the priority assigning unit110 may further assign the priority based on feedback time-delay of thePUCCH signal of the component carrier.

Preferably, when the priority is assigned by the priority assigning unit110 based on the feedback time-delay of the PUCCH signal of thecomponent carrier, a FDD component carrier may have a higher prioritythan a TDD component carrier, In addition, TDD component carriers withthe following configurations may have lower priorities in descendingorder: configuration 0, configuration 1, configuration 6, configuration3, configuration 4 and configuration 5. A TDD component carrier inconfiguration 2 may have the same priority as a TDD component carrier inconfiguration 3.

Further, the transmitting unit 120 may notify the user equipment 200 ofa message on setting and changing of the priority of the componentcarrier via a RRC signaling or a MAC signaling.

That is, when a priority is changed, the transmitting unit 120 maynotify the user equipment 200 of the changed priority via a RRCsignaling or a MAC signaling.

Further, when there are overlapping downlink subframes among themultiple component carriers and there is transmission of PDSCH on theoverlapping downlink subframes, the determining unit 130 may determinefeedback timing of a PUCCH signal corresponding to the component carrierfor which there is the transmission of PDSCH on the overlapping downlinksubframes, based on at least one of: feedback timing of a componentcarrier with the highest priority among uplink component carrierscorresponding to the component carrier for which there is thetransmission of PDSCH on the overlapping downlink subframes; feedbacktiming of a component carrier with the lowest feedback time-delay amonguplink component carriers corresponding to the component carrier forwhich there is the transmission of PDSCH on the overlapping downlinksubframes; feedback timing of a primary scheduling component carrier ina process of cross carrier scheduling; and feedback timing of thecomponent carrier per se for which there is the transmission of PDSCH onthe overlapping downlink subframes.

Preferably, in a case that the feedback timing of the PUCCH signal isdetermined by the determining unit 130 based on the feedback timing ofthe component carrier with the highest priority or the feedback timingof the component carrier with the lowest feedback time-delay, ifobtained time-delay gain or uplink transmission power gain is lower thana predetermined threshold and the number of downlink subframesassociated with uplink subframes for transmitting the PUCCH signal ofthe component carrier is caused to be increased and exceed two, thefeedback timing of the component carrier per se for which there is thetransmission of PDSCH on the overlapping downlink subframes may beselected by the determining unit 130 as the feedback timing of the PUCCHsignal.

Preferably, the determining unit 130 may select, as scheduling timing ofa PUSCH signal of the component carrier on the overlapping downlinksubframes corresponding to the overlapping downlink subframes, one of:feedback timing of the PUCCH signal of the component carrier; andscheduling timing of the PUSCH signal of the current component carrier.

Preferably, the determining unit 130 may determine the rule of thefeedback timing of the PUCCH signal based on at least one of time-delayrequirement of the downlink signal, energy saving requirement of theuser equipment, and implementation complexity.

Further, the notifying unit 140 may notify the user equipment 200 of thedetermination rule of the feedback timing of the PUCCH signal with whichthe component carrier is to comply via a RRC signaling or a MACsignaling.

Further, when it is required to adjust dynamically the PUCCH feedbackcarrier and/or the PUCCH feedback timing of the component carrierperforming PDSCH transmission on the overlapping downlink subframes, thedesignating unit 150 may designate dynamically the PUCCH feedbackcarrier on the overlapping downlink subframes and/or the feedback timingof the PUCCH signal corresponding to the PDSCH transmission of thecomponent carrier, by utilizing newly added bit information orredundancy for DCI of PDSCH scheduling.

Preferably, the designating unit 150 may designate dynamically the PUCCHfeedback carrier on the overlapping downlink subframes and/or thefeedback timing of the PUCCH signal corresponding to the PDSCHtransmission of the component carrier, by adding a bit to the DCI.

Further, the receiving unit 210 of the user equipment 200 may receive amessage on setting and changing of the priority of the component carriertransmitted by the base station 100. The receiving unit 210 may alsoreceive determination rule of feedback timing of a PUCCH signal to befollowed by a component carrier which is notified by the notifying unit140, and the PUCCH feedback carrier on the overlapping downlinksubframes and/or the feedback timing of the PUCCH signal correspondingto the PDSCH transmission of the component carrier which is designed bythe designating unit 150, and the like.

The selecting unit 220 may select a component carrier with the highestpriority among aggregated carriers in which overlapping of uplinksubframes occurs, and select scheduling timing of a PUSCH signal and thefeedback timing of the PUCCH signal according to the determination ruleof the feedback timing when overlapping of downlink subframes occurs inthe aggregated carriers.

The transmitting unit 230 may transmit an uplink signal through thecomponent carrier, the feedback timing of the PUCCH signal, and thescheduling timing of the PUSCH signal selected by the selecting unit220, or the transmitting unit 230 may transmit an uplink signalaccording to a component carrier, the feedback timing of the PUCCHsignal, and the scheduling timing of the PUSCH signal designateddynamically by a DCI signaling in the overlapping downlink subframes.

The various specific implementations of the respective units above ofthe wireless communication system according to the embodiments of thepresent disclosure have been described in detail previously, andtherefore the explanations thereof will not be repeated herein.

Apparently, respective operating processes of the method for performingwireless communication in a wireless communication system according tothe present disclosure can be implemented in a manner of a computerexecutable program stored on a machine-readable storage medium.

And, the object of the present disclosure can be implemented in a mannerthat the storage medium on which the computer executable program aboveis carried is provided directly or indirectly to a system or apparatus,a computer or a Central Processing Unit (CPU) of which reads out andexecutes the computer executable program. Here, the implementation ofthe present disclosure is not limited to a program as long as the systemor apparatus has a function to execute the program, and the program canbe in arbitrary forms such as an objective program, a program executedby an interpreter, a script program provided to an operating system,etc.

The machine-readable storage medium mentioned above includes, but is notlimited to, various memories and storage devices, a semiconductordevice, a disk unit such as an optic disk, a magnetic disk and amagneto-optic disk, and other medium suitable for storing information.

Additionally, the technical solution in the present disclosure can alsobe implemented by connecting a computer to a corresponding web site onthe Internet, downloading and installing the computer executable programaccording to the invention into the computer, and then executing theprogram.

FIG. 8 is a block diagram illustrating an exemplary structure of ageneral-purpose personal computer on which the method for performingwireless communication in a wireless communication system according tothe embodiments of the present disclosure can be implemented.

As shown in FIG. 8, a CPU 1301 executes various processing according toa program stored in a Read Only Memory (ROM) 1302 or a program loaded toa Random Access Memory (RAM) 1303 from a storage device 1308. In the RAM1303, if necessary, data required for the CPU 1301 in executing variousprocessing and the like is also stored. The CPU 1301, the ROM 1302 andthe RAM 1303 are connected to each other via a bus 1304. An input/outputinterface 1305 is also connected to the bus 1304.

The following components are connected to the input/output interface1305: an input device 1306 including a keyboard, a mouse and the like,an output device 1307 including a display such as a Cathode Ray Tube(CRT) and a Liquid Crystal Display (LCD), a speaker and the like, thestorage device 1308 including a hard disk and the like, and acommunication device 1309 including a network interface card such as aLAN card, a modem and the like. The communication device 1309 performscommunication processing via a network such as the Internet. Ifnecessary, a drive 1310 can also be connected to the input/outputinterface 1305. A removable medium 1311 such as a magnetic disk, anoptical disk, a magneto-optical disk, a semiconductor memory and thelike is mounted on the drive 1310 as necessary such that a computerprogram read out therefrom is installed in the storage device 1308.

In a case that the series of processing above is implemented insoftware, a program constituting the software is installed from thenetwork such as the Internet or the storage medium such as the removablemedium 1311.

It is understood by those skilled in the art that the storage medium isnot limited to the removable medium 1311 shown in FIG. 8 in which theprogram is stored and which is distributed separately from the device soas to provide the program to the user. Examples of the removable medium1311 include a magnetic disk including a Floppy Disk (registeredtrademark), an optical disk including a Compact Disk Read Only Memory(CD-ROM) and a Digital Versatile Disc (DVD), a magneto-optical diskincluding a MiniDisc (MD) (registered trademark), and a semiconductormemory. Alternatively, the storage medium may be the ROM 1302, the harddisk contained in the storage device 1308 or the like. Herein, theprogram is stored in the storage medium, and the storage medium isdistributed to the user together with the device containing the storagemedium.

In the system and method of the present disclosure, it is obvious thatrespective components or steps can be decomposed and/or recombined. Suchdecomposition and/or recombination should be considered as an equivalentsolution of the present disclosure. And, the steps performing a seriesof processing above can be performed in the describing order naturally,but this is not necessary. Some steps can be performed concurrently orindependently with one another.

Although the embodiment of the present disclosure has been described indetail in combination with the drawings above, it should be understoodthat, the embodiment described above is only used to explain theinvention and is not constructed as the limitation to the presentdisclosure. For those skilled in the art, various modification andalternation can be made to the above embodiment without departing fromthe essential and scope of the present disclosure. Therefore, the scopeof the present disclosure is only defined by the appended claims and theequivalents thereof.

1-13. (canceled)
 14. A method for performing wireless communication in awireless communication system, the wireless communication systemcomprising a first base station and a user equipment (UE), the methodcomprising: communicating from the UE with the first base station via afirst component carrier and a second component carrier; andcommunicating from the UE with a second base station via a thirdcomponent carrier, wherein a coverage area of at least two of the firstcomponent carrier, the second component carrier, or the third componentcarrier, are different.
 15. The method according to claim 14, wherein, acoverage area of the first component carrier is larger than a coveragearea of the second component carrier; and the coverage area of thesecond component carrier is larger than a coverage area of the thirdcomponent carrier.
 16. The method according to claim 14, wherein, afrequency of at least two of the first component carrier, the secondcomponent carrier, or the third component carrier are different.
 17. Themethod according to claim 16, wherein, a frequency of the firstcomponent carrier is lower than a frequency of the second componentcarrier; and the frequency of the second component carrier is lower thana frequency of the third component carrier.
 18. The method according toclaim 14, wherein, the communicating from the UE with the first basestation includes performing carrier aggregation with the first componentcarrier and the second component carrier.
 19. The method according toclaim 14, further comprising, communicating from the UE with the secondbase station via a fourth component carrier, wherein, at least two of acoverage area of the first component carrier, a coverage area of thesecond component carrier, a coverage area of the third componentcarrier, and a coverage area of the fourth component carrier aredifferent.
 20. The method according to claim 19, wherein thecommunicating from the UE with a second base station via the thirdcomponent carrier includes communicating with the second base stationvia the third component carrier and a fourth component carrier incarrier aggregation.
 21. The method according to claim 14, wherein, thecommunicating from the UE with the first base station via the firstcomponent carrier and the second component carrier includes the UEcommunicating with the first base station and the second base station ata same time via the first component carrier and the third componentcarriers in dual connectivity.
 22. The method according to claim 21,wherein, in the dual connectivity, the UE further performs communicatingwith the first base station via the second component carrier.
 23. Themethod according to claim 19, further comprising: performing dualconnectivity, wherein the UE further performs communicating with thesecond base station via the third component carrier and the fourthcomponent carrier.
 24. The method according to claim 14, wherein,selecting a candidate component carrier from the first component carrieror the second component carrier based on which component carrier has alower expected power loss.
 25. The method according to claim 14,wherein, the first base station is a macro base station, and the secondbase station is a micro base station.